In the Automatic Identification and Data Collection (AIDC) industry long range barcode reading is generally achieved using laser scanning or 2D imaging. Both methods have drawbacks, primarily due to poor signal to noise ratio of the detected signal. For example, when using a laser detector, the beam must be focused over a long distance to ensure that a barcode can be read.
RFID is not typically used in these applications because RFID is non-directional, so targeting a specific item to be read is difficult in an environment when there may be many RFID tags essentially co-located.
In order to allow the encoding of larger amounts of data in a single bar code symbol, a number of 1D stacked bar code symbologies have been developed which partition encoded data into multiple rows, each including a respective 1D bar code pattern, all or most all of which must be scanned and decoded, then linked together to form a complete message. Scanning still requires relatively higher resolution in one dimension only, but multiple linear scans are needed to read the whole symbol.
A class of bar code symbologies known as two dimensional (2D) matrix symbologies have been developed which offer orientation-free scanning and greater data densities and capacities than 1D symbologies. 2D matrix codes encode data as dark or light data elements within a regular polygonal matrix, accompanied by graphical finder, orientation and reference structures.
Conventionally, a reader, whether portable or otherwise, may include a central processor which directly controls the operations of the various electrical components housed within the bar code reader. For example, the central processor controls detection of keyboard entries, display features, trigger detection, and bar code read and decode functionality.
Efforts regarding such systems have led to continuing developments to improve their versatility, practicality and efficiency.
It will be appreciated that for purposes of clarity and where deemed appropriate, reference numerals have been repeated in the figures to indicate corresponding features. Also, the relative size of various objects in the drawings has in some cases been distorted to more clearly show the invention.